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vaapi_encode_h26x.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include <stdint.h>
20 
21 #include "vaapi_encode_h26x.h"
22 
24  uint8_t *src, size_t src_bit_len)
25 {
26  size_t dp, sp;
27  int zero_run = 0;
28  size_t dst_len = *dst_bit_len / 8;
29  size_t src_len = (src_bit_len + 7) / 8;
30  int trailing_zeroes = src_len * 8 - src_bit_len;
31 
32  if (dst_len < src_len + 4) {
33  // Definitely doesn't fit.
34  goto fail;
35  }
36 
37  // Start code.
38  dst[0] = dst[1] = dst[2] = 0;
39  dst[3] = 1;
40  dp = 4;
41 
42  for (sp = 0; sp < src_len; sp++) {
43  if (dp >= dst_len)
44  goto fail;
45  if (zero_run < 2) {
46  if (src[sp] == 0)
47  ++zero_run;
48  else
49  zero_run = 0;
50  } else {
51  if ((src[sp] & ~3) == 0) {
52  // emulation_prevention_three_byte
53  dst[dp++] = 3;
54  if (dp >= dst_len)
55  goto fail;
56  }
57  zero_run = src[sp] == 0;
58  }
59  dst[dp++] = src[sp];
60  }
61 
62  *dst_bit_len = 8 * dp - trailing_zeroes;
63  return 0;
64 
65 fail:
66  *dst_bit_len = 0;
67  return AVERROR(ENOSPC);
68 }
#define src
Definition: vp8dsp.c:254
uint8_t
#define sp
Definition: regdef.h:63
#define AVERROR(e)
Definition: error.h:43
#define fail()
Definition: checkasm.h:89
int ff_vaapi_encode_h26x_nal_unit_to_byte_stream(uint8_t *dst, size_t *dst_bit_len, uint8_t *src, size_t src_bit_len)